Preparation of halogenated olefines



Patented Aug. 3, 1954 .UNITED- Y STAT S 'Jareaw clark; charleston, W. ya., assigner to `Union Carbide and CarbonCorporation;l woor-- poration of New York No Drawing. MApplication@February25, 1953,

Serial No. 338,897

(erase-*653) lll'Claims.

. l vThis improvement relatesv to halogenate'd olenes. `More particularly it is concerned with an improved process wherein chlorotriiii'ioroethylene is made by. the removal of chlorine from 1,1',`2trichloro1,2,2trifluoroethane in the presence of hydrogen and over a nickel catalyst. It is known (locke et al. J. A. C; S. (1934), vol. 56,1726) that polychlorofluoroalkanes canbe dechlorinated with zinc toyield chlorofluoroalkenes. The reaction appears to be generally applicable to the dehalogenation of compounds having one ormore chlorine. or'bromi-ne atoms on each of adjacent carbon atoms. `It constitutes, also, a method for` preferentiallyV removing chlorine and bromi-ne atomsffrom compounds'of lthis type in which uorine is'additionally present. The chlorine-or bromine .atoms areV removed in pairs,A with one atom ofzinc being required. to effect the removal 'of each pair. 'Thus, the dechlorination of trichlorotriuoroethane, for instance, by this processresults in the production of by-p'roduct .zince chloride Vin an amount which is 1.2 times the weight-of the chlorotriluoroethylene that is desired. This zinc chloride is iinally obtained as an aqueous solution. On a largescale its disposal would constitute aV d'iicult and vserious problem sincethe regeneration of the'zinc or the recovery of the contained halogen is not practicable, atleast not at the present time. Thereaction has the' additional disadvantage 'of being carried out underpressure, in the liquid phase.

It-is known also that halogens can be removed fromv halogenatecl organic compounds-in the presence of hydrogen and this reaction 'has been applied as a quantitative procedure for the ndetermination of the amount of halogen present. Sabatier and Maihle have described (Comptes rendu (1904) Vol. 138; 407) the reaction of hexachloroethane and hydrogenover a nickel catalyst with the formation of perchloroethylene and` hydrogen chloride.

More recently, theuse ofcopper and iron as catalysts, 'has'vbeen lsuggested (U. S.- Patent v2,564,- 919) in the reactionk of polychlorohydrocarbons and hydrogen toform oleiines. In acknowledging prior art, the patent stated that halooleiines such as cisand transdichloroethylenes have been preparedpreviously ley-the vapor-phase reaction-of hydrogen with polyhalohydrocarbons using iron lings but went on to pointout that 'with nickel the-.conversions have been poor while with iron'thcv yields have beenpoor and the proce ess .generally unsatisfactory.

Theipresent eimprovement is` based on -my disparts of -the precipitated salts.

2 covery that chlorotrifuoroethylene ecan be produced in'relatively good yieldsy Yand'eilicienciesby removing chlorine' preferentially from '1,1,2itri chloro#122,2trifluoroethane in the' presence of hydrogen over a" supported nickel catalyst. 'Hydrogen chl'orideis formed.- along'w'ith the 'main product. Thefreactin isiillustratedby thefollowing equation:

CFCliCF'zCl+H2-$CFC1F2+2HC1.

v'Thef'react'ion is carried'A out by v"passing Ja mixture of 1,1 ,'2trichlro-l,2,'2#triuoroethane and hyd'i'iogen through aie'actor or converter maintained'at an' 'eleva-ted" temperature. l Thefreactcr can'bea length of tube made ofnicjkelo'r of "stainless steeLfor'instance, charged with the catalyst as hereinafter described. `Known eiipedients can be employed zfor heating thev reactor and maintaining itat a'desired` temperaturaasifor instance, an electrical resistance,"or' a salt bath inwhich the 'reactor'is immersed'. kThe vapors issuing from Vthe reactor are collected by cooling and' condensation, if'desired, `after'having first been washedto're'rnove the hydrogenhalide, and dried; or by' other suitable. expedient.'

Preffably *he "Catalyst 'Supporta `tarnm phosphate; "calciumv phosphate; o'r calcium i fluoride phosphate. The' supportedl'catalysts 'can' be prepared by coprecipitation of the phosphatesof nickel andcalci'm 'or nickeland'bariur'n'fromlsolutio'ris of v`soluble 'salts of t'hese" in'etals, asl for instance by pouring'dilute aqueous ammonium hydroxide and a solution of l nickel chloride vand barium chloride acidified'with phosphoric acid simultaneously into'v/ater. The rates of addi-- tionv of'the two -sfnlution's should rbe so 'adjusted relative t'o 'each other that the precipitation takes place 'under "substantially 'neutral conditions. By the Vterm substantiallyfneutralf conditions Iis Vniearita pH in the' rangefof ab'ut`6.0"to` 8j;5. The coprecipitated's'alts arethen` Washed,` driedi'an'd screenedy to' a line powder. My' supported 'catalyst`is.best'usedin the form of lsmall pellets, as for instance, in the form of small cylinders; about fia-inch .i'n' diameter by v`i-inch long. v'In pelleting the cop-recipit'ated'salts are mixed with Na s-'mall amount bf graphite, 'of 'the order of v`about Zpartsper 1'00` parts of the precipitated salts. A s'iytiall A alnc'ilihty of "powdered ChrOI'nC O'X'deV may 'also be added, rif-desired, attneumethe' catalyst i-s pelleted,of. the order o'f about one'part'per 100 The presence ofchroinic oxide .in the catalyst is not necessary, however. The graphite is subsequently'oz'iidized prior to use ofthe catalyst.

Prior to putting the pellets into use for producing chlorotriiiuoroethylene, the graphite is removed by oxidation with air at an elevated temperature of about 600 C. in the presence of steam. After purging the carbon-free catalyst with nitrogen with the temperature reduced to about 430 C. to 450 C., hydrogen is passed over the catalyst to reduce the nickel compound to metallic nickel.

Without desiring to be bound by any particular theory of catalytic operation, it is believed that it is the metallic form of nickel which is active. The nickel phosphate is presumably reduced to the free metal, at least on the surface of the catalyst pellets, during treatment with hydrogen prior to initiating the formation of chlorotrii'luoroethylene. Further evidence that the metal is the active form of the catalyst is to be found in the fact that increased activity of the catalyst is observed after allowing a slow stream of hydrogen to flow over it during shutdown periods, as for instance during an overnight shut-down following a period of operation. This increase in activity is attributable, it is believed, to at least a partial reduction of accumulated nickel halides to the free metal.

In producing chlorotrifluoroethylene from 1,l,2trichloro-1,2,2-trifluoroethane over my supported nickel catalyst in the presence of hydrogen, the ratio of hydrogen to the trichlorotrifluoroethane is not narrowly critical. At a ratio of 0.75 mole of hydrogen per mole of the trichlorotriiiuoroethane, it is possible to react practically all of the hydrogen, thereby facilitating recovery of the chlorotrifluoroethylene and unreacted trichlorotrifluoroethane. Increasing the proportion of hydrogen increases the yield of chlorotrifluoroethylene but the losses to carbon and triiiuoroethylene also increase. A ratio of from 0.75 to 3 moles of hydrogen per mole of 1,l,2trichloro-1,2,2-triiiuoroethane is preferred.

The actual mechanism of the dechlorination is not known. As pointed out above, it may be that the nickel functions as a catalyst by reacting to form the metal chloride which then reacts with the hydrogen to give hydrogen chloride, with the free metal being regenerated and the cycle repeated. Appreciable removal of chlorine is effected at temperatures as low as 200 C. but at this temperature the reduction of nickel halide is very slow so that the metallic nickel catalyst tends to be converted to the less active nickel chloride and fluoride. Temperatures in the range from 400 C. to 475 C. are preferred. Usable temperatures range up to 525 C. but at temperatures above 475 C. the reaction tends to become less efcient due to lessened selectivity in removing chlorine preferentially, and a somewhat shorter contact time than that used at lower temperatures is recommended.

Also, losses to carbon and triiiuoroethylene can be minimized by using lower temperatures to eifect lower single pass yields. Under such conditions, however, any mechanical losses are greatly magnied in terms of decreased efficiencies. Hence, precautions are required to minimize mechanical losses. In general, the optimum efficiencies are obtained when the single pass yields are in the range of 20 to 40 per cent, based on the 1,1,2-trichloro-1,2,2-trii'luoroethane.

My supported nickel catalyst exhibits a high initial activity which falls oif rapidly during operating periods of two to three hours, and the activity then declines much more gradually over subsequent periods of fteen to thirty hours. A

possible explanation of the initial rapid decline is thepartial conversion of metallic nickel to a mixture of nickel chlorides and iiuorides. The subsequent slow falling-oif of activity is quite likely due to an accumulation of polymeric material or of free carbon or both on the surface of the catalyst. At the end of a run such deposits can be removed by oxidation with air at temperatures 'm the range of about 450 C. to 600 C. The resulting oxidized catalyst is then reduced with hydrogen at about the temperature at which it is to be used for the production of chlorotrifiuoroethylene. This oxidation and reduction treatment results in the restoration of a spent catalyst to approximately its initial activity.

According to my studies, the maximum time that it has been possible to obtain economical conversions of 1,1,2 trichloro 1,2,2 trifluoroethane to chlorotriuoroethylene with supported catalysts rbefore reactivation is required is about thirty-five hours operation. Also, according to my studies, another material which has suiiicient stability to the coproduct hydrogen chloride and side-reaction product hydrogen iiuoride at the operating temperatures necessarily employed is activated carbon. My supported catalyst is not only stable to hydrogen chloride and hydrogen fluoride under reaction conditions, but has the additional advantage as compared to an activated carbon support, that the carbonaceous deposits which invariably form on the catalyst surface during operation can be removed by air oxidation. The ability of my supported catalyst to withstand repeated reactivations is especially important in the production of chlorotriiiuoroethylene commercially in large scale reactors.

Granular refractory materials such as pumice, silica gel, alumina gel, porcelain or iire brick, and the like, are not suitable as catalyst supports in my process. With the exception of alumina gel, all of the above-named materials contain silica which is attacked by hydrogen fluoride. While it is true that the amount of hydrogen fluoride that is formed in the conversion of 1,1,2- trichloro-1,2,2-triluoroethane to chlorotrifiuoroethylene is small, it is also true nevertheless that this small amount attacks the silica-containing supports, 'with consequent disintegration.

Also, use of fused aluminum oxide (Aloxite) as a support results in low yields and efficiencies. One possible explanation is the effect of the surface characteristics of this support on the reaction but it is also to be borne in mind that there also could be formed some aluminum chloride. AAluminum chloride is known to effect the replacement of fluorine with chlorine and also to bring about rearrangements and disproportionations.

The improvement is further illustrated by the six examples which follow.

EXAMPLE 1 Eighty grams (0.33 mole) of nickel chloride hexahydrate (NiClz-l-GHzO); 704 grams (2.9 moles) of barium chloride dihydrate (BaClz-lr-2H20) and 254 grams of aqueous per cent) phosphoric acid (2.2 moles) dissolved in suiiicient water to make 6 liters of solution was poured into 0.9 liter of water simultaneously with 2.4 liters of dilute aqueous ammonia containing grams (7.1 moles) of NH3. The solutions were mixed gradually over a three-hour period, and

the`pI-Lofthefresultingrmiiturewas maintained in? the range" of "'6i0 vtof85'id .uring' thee perie'drbyf-7 adjusting` the-relative rates Aof LadditionMof the two solutions.' jNickel-andi barium- --salts were coprecipi,tatediy and the volume ofthese-coprecipitateci'salts ,aft-era settling; periodiciv onehour was 2.5' liters: Thisprecpitate' wasewash-ed with Waterwsevenitimes bydecantationusing-a volume ratio of water to settledprecipitateof-aboutlto v1. After iiltering andixalrying overnight at a temperaturedof -8,5 C., i,there was obtained 515 grams. of'fmixedlharium l.and nickel phosphates;

.This material was.passedthrough a screen havcomprisne-about 18.inches .of coilednickelscreen was provided at the upper end'of theypipaand the bottom of the catalyst bed was supported ona nickel ring positioned about 14 inches above theA bottom Iof the= jaeketed f part of the tube.

Initially; the `catalyst was heated at --a temper--l aturerthatwas-gradually increased at'the rate of50 C. perhourzuntil an endtemperature of 660",C. was reached. and steamwerethen introduced'*ata rateof .13liters per hour and 200jgramsper= noun-respectively, for the purpose fr 'emoVin-g` fromfthecatalyst, by oxidation in the presence of 'steamythe carbon Y originallyv incorporated-'inthe catalystin theform ofgraphite. As-tlfie oxidation proceeded, --the air/feed was gradually increased to a final rate-v of` 46 liters per hour. After 'all the-carbon had been removed, the .reactor was purged with nitrogen and'gthe 'temperature allowed to` decrease `to a range ofabout` 430 C. 'tof-'450 C; 'While'the temperature was maintained within this'range, hydrogen wasl passed' into the reactorfor anper'iod of j1' 5"hoursat aratey ofllS liters'perhour.

Chlorotrifluoroethylene was 'produced' `b'y--passing 1,1;2trichloro-1;2,2trifluoroethanein contact withthe catalyst Aof Example V1 inthe presenceof hydrogen andata reactionJ temperature man1/tained' at4 448 C. to 454 .'C. The initial activity of the catalyst' was` very khigh `and in orderpartly to compensate for this'high activity', the `trichlorotriluoroethane was 'fed at a 'high lspace'velocity which,`it was estimated, would give approximately a '25 to 30V per cent conversion `to chlorotriuoroethylene. The initial feed rates .were '740 grams of the trichlorotrifluoroethane `and 118 liters of hydrogen, per hour, which were maintainedfor a period of 3.5 hours. Thereafter-and until the reaction was stopped Vfor reactivation oithe catalyst, Vthe rates were .main-,- tained at. 38,3` grams of4 trichlorotriliioroethane andw59litersof hydrogen per.` hour. During `the mst. 3.5 hours .of operation there. .was produced 2,254 grains .of .washed .crude material. Upon distillation of this material; there was obtained 388 grams of chlrotriiiuoroethylene, correspond- :ingfto a.yield `of 24.1;.perf'centand an eflici'ency of. 7.8.8. per cent. `After the catalystfhad :been i-in servicer .'15 lhours, .zafsucceeding period o' r opera- .liion of:5:5 hours-gave. 3,09 `grains .of zchlorotri.-

6 fluoroethylene which; corresponded" to #ayifeld of 23:4per--fcent-anatan efficiencyv off'7 'I-Gf'per 'centi'A EXAMPLEB Subsequent to the run ofEi'zample 2, the catalyst 'Was-reactivated by Aoxidation with'eair 'followedf by reduction' with *hydrogen as 'dese lied for the-initialpreparation of fthe scatalyst f ain-ple j1. l 44Feeding 1781;l grams-pery hour-*f fit1-22' trichleroe1,2',2etriluoroethane ftogether'=with 1 1I=8 liters -per houroflriydi'ogeny over vthel reactivated catalyst; ymaintainedatria temperature of #4495-1-2. to 453' C. gave122 grains='of-"organi`c prdduet's and 2-541grams (6291mo1es) of -coproduet hydrogen halideeover- `a"reactienperiod- 4of "2".5'fhours:` Upen distillation of 'the organic products, there @was obtainedl357l grams "(3.1 moles) Vof cliloretiiine roethylene and 1216 grams (6.5 moles ofi-nn reacted trichlorotriuoroethane: The-"yield'eand efficiency-*to chlorotriiiuoroethylenelwere; 'ea-leu,-1 latedtobe *291;41per eentfandl'lfper cent): respeeh tively. Thecatalyst pellets 'aiter'a-totaTfon stream Ltime o'iVA 3225 hoursY `were still har'ii lan-d in excellent condition -for-l continued 'use'.

v vl'rlXAli/DDLE .4

`lOne-hundred sixty grams (016.7 malerei-nickel chloride hexahydrate .'(NiClz-l-'iG-I-IzO) 595.1.gra-ms (5.4 moles) of calcium chlorideand'53if1grams (0.46 mole) :of aqueous (85-vper` cent) iorth'op'hcplioric acid. dissolved y in.I -suiiicient lwater to4 make up 5.8 liters of solution-Was poure'dinrtotgfliter of water simultaneously wilthl2.7 liters-of atsolution containing 135 grams (z'meleswoflaqueeus ammoniumlhydroxide (28 per centr-and 1008 grams-(10'.'7 moles). of 'potassiumiiueride dihy-a drate (KCl-P21120) 'The l pI-l.4 yof thearesulting slurry was rmaintained Lin Ithe range-'oi 6.0' y to? $20 by adjusting therel-ative rates 'offadditionfof'ftlie two solutions, andby-addingin .two portions an additional '75 grams (1.2 moles) of aqueous ammonium hydroxide (28 per cent). A period of 2.3 hours :was :required to. complete .the mixing. Thief-precipitate, *after ywashing by, decantation, vfiltering andrdrying, weighed-435 grams. .It was puluerized,..passed through a 3.5 mesh screeniand mixed with .4.5 4grams (1 per cent) :of-chromimn oXideand-.Qgrams (2 percent) ozgraphite ais allubrieant to1faci1itatefpel1eting. .Thea-.resulting mixture .wascthenpelleted A .0.25 liter (22() grams) samplesofthe-:catalyst ofi/Example 4..,was charged.r to A.tlievsa=lt=bathf.i etedreactor-.described v'in Example 2'. 'Ihiecon-` tained. graphite which wasadded to `facilitateriel.v leting' waszremovedby oxidation inair atattemfperature. which ranged'frem 261CLto=648 C. The. air feedzirate .which :wa-S liters y'at thef-start was increasedgraduallyto aiinal rate.of-175' liters per hour. After the oxidation treatment `was completed, :air 'was l purged lfrorn the'reactor-with nitrogen and the vreactor allowed: tocool down to; avtemperature `of 425 C. Ato 450 C. Hydrogen v.wasfthen passed through the -reactorfat thisitemperature at the rate of 118 liters-.per'hourl'for a period :.of .3.7 hours to Y*reduce the. catalyst.'

EXAMPLE -5 The catalyst of Example 4 eXhbited-af-hfigh Ainitial activity'similar to thatcbserved witlf1'-t`li"e chloro#1,2;2-triuoroethane at the rate "of v'T53 grams per hour togetherwithll'lliters per 'hour yof'V hydrogen over vthe catalyst ".maintained atta ftemperature. of 447 CL `tov '453 C., .-thereiwas;ob tained, .over a .2:5 period, ..395 1 gramszaof F chloz trifluoroethylene, corresponding to a yield of 33.7 per cent, with an erliciency of S per cent based on the trichlorotriluoroethane.

EXAMPLE 6 At the end of the 2.5-hour run of Example 5, the feed rate of the trichlorotrifluoroethane was reduced by half to a rate of 382 grams per hour. There was produced 245 grams of chlorotriuoroethylene corresponding to a yield of 26 per f cent. The catalyst was then restored to essentially its initial activity by oxidation with air followed by reduction with hydrogen. Using about the same feed rates as were employed ior a 3.5- hour period in Example 2, there was obtained 366 grams o1" chlorotriiiuoroethylene over an operating period of 2.5 hours, corresponding to a yield of l31 per cent.

lThe nature and extent of the foregoing improvement is further illustrated by way of contrast by the following Experiments A., B and C which form no part of the present improvement. According to my studies set forth in Experiment A, a copper catalyst made by coprecipitation of copper and calcium phosphates is inferior to my catalyst in that maximum observed efficiency of the former was only 74 per cent, and fell off at the end of 7.5 hours use to 64 per cent. Production ratios were also lower.

According to my studies set forth in Experiment B, the iron catalyst supported on activated carbon was very ineffective.

Also according to my studies set forth in Experiment C, the yields and efficiencies obtainable with Raney nickel pellets were almost as high as those obtainable with my supported nickel catalyst. The big disadvantage was that the pellets disintegrated with resultant excessive back pressure after about fourteen hours of service.

EXPERIMENT A Part 1 Calcium phosphate and copper phosphate were coprecipitated by adding an aqueous solution of the chlorides of the metals simultaneously with 2.9 liters of a 3.1 normal aqueous ammonium hydroxide solution to a liter or" water over a period of 1.4 hours. The solution of metal chlorides contained 486.5 grams (3.31 moles) of calcium chloride dihydrate, 51.2 grams (0.381 mole) of cupric chloride, and 292 grams of aqueous (85 per cent) phosphoric acid (2.54 moles) in a total volume of 7.0 liters of solution. During the addition, the pH of the mixture was maintained in the range of 6.0 to 7.0 by adjustment of the rates of addition of the two solutions relative to each other. The precipitate that was formed was a1- lowed to settle by standing overnight. The settled precipitate which occupied 7 liters was washed by decantation nine times using to 13 liters of distilled water each time, and then dried at a temperature of 140 C. The dried coprecipitated phosphates amounting to 392 grams were passed through a 35-mesh screen mixed with 9.8 grams (2.5 per cent by weight) of powdered graphite, and compressed into pellets which were approximately 15s-inch by rse-inch.

The pelleted catalyst having a volume of about 0.25 liter, was charged into a reactor which was a nickel tube (one-inch inside diameter) provided with a salt bath heater. The graphite was oxidized by passing l0 liters of air over the catalyst in a period of one hour while the catalyst was heated from 310 C. to 436 C. Thereafter, the air feed was maintained at a rate of 30 liters per hour for a period of 2.2 hours while the temperature was gradually increased from 436 C. to an end temperature of 535 C. At the end of the 2.2 hour period, the oxidized catalyst was purged with nitrogen and allowed to cool to 480 C. The catalyst was next reduced by passing hydrogen over it at a rate of 118 liters per hour for a period of 1.7 hours while the temperature was maintained at 460 C. to 490 C.

Part 2 Chlorotriluoroethylene was produced by feeding l,1,2-trichloro-1,2,2-triluoroethane and hydrogen over the catalyst of Experiment A, Part 1, at the rates of 770 grams per hour and 118 liters per hour, respectively, for a period of 2.0 hours while the catalyst was maintained at s, temperature of 447 C. to 452 C. There was obtained 1308 grams oi organic condensate which yielded, upon distillation, 224 grams of chlorotriuoroethylene together with 6 grams of trifiuoroethylene and 1052 grams of unreacted trichloroiiuoroethane. There was also another fraction of 26 grams which was not credited to the above amounts. The yield and efficiency to chlorotrifluoroethylene were 23.5 per cent and 74 per cent, respectively.

Part 3 Following the run described in Part 2 of EX- periment A, intermittent operations were continued with the catalyst for a period of 5.5 hours. For the last 5.5 hours, thevfeed rates were reduced to one-half of those employed in Part 2. The yield and eiiciency for the nal 3.5 hours were i8 per cent and 64 per cent, respectively.

Thus, the eiiiciency using the supported copper catalyst of this experiment which was initially below that obtainable with my supported nickel catalyst dropped further to 64 per cent after only a few hours of service.

EXPERIMENT B A solution containing 33 grams of ferric chloride, grams of aqueous hydrochloric acid (37 per cent, hydrogen chloride) and 87 milliliters of water was evaporated to dryness on 0.3 liter of activated carbon passing a screen having 4 meshes per inch and being retained on a screen having 6 meshes per inch. The resulting catalyst of ferrie chloride on an activated carbon support amounting to 0.2 liter grams) was charged to a reactor which was a three-foot length vof stainless steel tube (one inch, inside diameter) provided with resistance windings for direct heat. The preheater and discharge end sections of the tube were packed with carbon rings. 1,1,2-trichloro-1,2,2-trifluoroethane and hydrogen were fed over this catalyst for a period of 4.5 hours at an average rate of 400 grams of the trichlorotrifluoroethane and 83 liters of hydrogen per hour. The catalyst temperature at the start was 410 C. and during the course of the reaction it was increased gradually to a iinal temperature of 440 C. to 460 C. There was obtained 1499 grams of condensate which on distillation gave only 15 grams of material boiling in the range of chlorotriluoroethylene, corresponding to a yield of 1.3 per cent which was practically negligible as compared to those obtained with my supported nickel catalyst.

EXPERIMENT C One-half liter (943 grams) of Raney nickel pellets (-inch by Tag-inch) was charged to a reactor which was a seven-foot length of nickel tubing (one inch, inside diameter) provided with a salt-bath heating jacket. The portions of the4 tube preceding and following the Raney nickel catalyst Were packed with solid nickel pellets. After a preliminary S-hour trial run or experiment under conditions similar to those described below, 2554 grams (13:62 moles) of 1,1,2-trichloro- 1,2,2-trifluoroethylene and 425 liters of hydrogen were fed over the catalyst during a period of 3.5 hours. The catalyst was maintained at a temperature of 400 C. t0 410 C. There was collected 1959 grams of condensate which on distillation gave 504 grams (4.33 moles) oi' chlorotriiiuoroethylene, 11.5 grams (0.14 mole) of trifluoroethylene, and 1436 grams (7.55 moles) of unreacted trichlorotriuoroethane. By-product halogen acid amounting to 16.2 moles was co1- lected in a water scrubber. The yield and eiciency to chlorotriluoroethylene were calculated to be about 32 per cent and 73 per cent, respectively.

It is to be noted that the eiiciency is inferior to the efficiencies of 78 to 80 per cent obtainable With my supported nickel catalyst. A more serious disadvantage Was the disintegration of the nickel pellets after about 14 hours of operation. The disintegration took place to such an extent that excessive back pressure developed through the catalyst bed preventing further operation.

This application is in part a continuation of my application Serial No. 209,196, filed February 2,1951.

'What is claimed is:

l. A process for making chlorotriuoroethylene which comprises heating a mixture of 1,1,2-trichloro-1,2,2-trifluoroethane and hydrogen in the presence of a catalyst at a temperature of from 200 C. tok 525 C., said catalyst being nickel supported on calcium phosphate.

2. A process for making chlorotriuoroethylene which comprises heating a mixture of 1,1,2-trichloro-l,2,2-triuoroethane and hydrogen in the presence of a catalyst at a temperature of from 200 C. to 525 C., said catalyst being nickel supported on barium phosphate.

3. A process for making chlorotriiluoroethylene 4. A process for making chlorotriiuoroethylene which comprises heating a mixture of 1,1,2-trichloro-1,2,2-trifluoroethane and hydrogen in the 10 presence of a catalyst at a temperature of from 400 C. to 475 C., said catalyst being nickel supported on calcium phosphate.

5. A process for making chlorotrifluoroethylene which comprises heating a mixture of 1,1,2-trichloro-1,2,2-trifluoroethane and hydrogen in the presence of a catalyst at a temperature of from 400 C. to 475 C., said catalyst being nickel supported on barium phosphate.

6. A process for making chlorotriuoroethylene Which comprises heating a mixture of 1,1,2-trichloro-1,2,2-triluoroethane and hydrogen in the presence or" a catalyst at a temperature of from 400 C. to 475 C., said catalyst being nickel supported on calcium iiuoride phosphate.

7. A process for making chlorotrifluoroethylene which comprises heating a mixture of 1.1.2-trichloro-1,2,2triuoroethane and hydrogen in the presence of a catalyst at a temperature of from 200 C. to 525 C., said catalyst being nickel supported on one of the group consisting of calcium and barium phosphates and calcium fluoride phosphate.

8. A process for making chlorotriuoroethylene Which comprises heating a mixture of 1,1,2-trichloro-1.2,2-trifluoroethane and hydrogen in a ratio of from 0.75 to 3 moles of hydrogen per mole of the 1,1,2-trichloro-1,2,2-triuoroethane in the presence of a catalyst at a temperature of from 200 C. to 525 C., said catalyst being nickel supported on one of the group-` consisting of calcium and barium phosphates and calcium fluoride phosphate.

9. A process for making chlorotriiuoroethylene Which comprises heating a mixture of L12-trich-loro-1,2,2-triuoroethane and hydrogen in the presence of a catalyst at a temperature of from 400 C. to 475 C., said catalyst being nickel supported on one of the group consisting of calcium and barium phosphates and calcium fluoride phosphate.

10. A process for making chlorotrifluoroethyl ene which comprises heating a mixture of 1,1,2- trichloro-1,2,2-trifluoroethane and hydrogen in a ratio of from 0.75 to 3 moles of hydrogen per mole of the 1,1,2-trichloro-1,2;2-trifluoroethane in the presence of a catalyst at a temperature of from 200 C. to 525 C., said catalyst being nickel supported on one of the group consisting of calcium and barium phosphates and calcium iluoride phosphate.

No references cited. 

1. A PROCESS FOR MAKING CHLOROTRIFLUOROETHYLENE WHICH COMPRISES HEATING A MIXTURE OF 1,1,2-TRICHLORO-1,2,2-TRIFLUOROETHANE AND HYDROGEN IN THE PRESENCE OF A CATALYST AT A TEMEPRATURE OF FROM 200* C. TO 525* C., SAID CATALYST BEING NICKEL SUPPORTED ON CALCIUM PHOSPHATE. 